What is eggfreezing?

Freezing / cryo preservation of eggs is process in which the oocytes are treated with cryoprotective substance and submerged in liquid nitrogen (-196degree C).

Why is eggcryopreservation done?

Oocyte cryopreservation via vitrification is one of the techniques used in preserving a woman’s fertility when she is young and the eggs are of higher qualitytherefore allowing reproductive capacity to be postponed until the time is right.

What percentages of eggs do survive after thawing?

With the vitrification process, preserved oocytes have same viability is more than 95% . Oocytes with not good quality may not survive after thaw process.

Who can benefit of oocyte freezing?

  1. In women diagnosed with cancer, before commencing their radiation or chemotherapy.
  2. Women who are delaying their childbearing for personal reasons (late marriage, family history of premature ovarian failure/early menopause).
  3. For oocyte pooling, in women with poor ovarian reserve, where patients request for multiple egg retrievals to pool the oocytestill a fair number of oocytes are obtained. Later the oocytes are thawed and ICSI(intra cytoplasmic sperm injection) is done.
  4. When husband fails to provide sample on IVF procedure day due to anxiety or if the sperm count is nil or has very poor quality sperm.

How is oocyte freezing done?

The steps to prepare the patient’s body for retrieval are the same as a fresh cycle retrieval.First,we stimulate the female’s ovaries with hormones to aid in multiple follicle growth.

The eggs are evaluated by the embryologists to determine if the eggs are mature. Eggs that are mature will be frozen. The immature eggs are cultured for an additional day, and will then be frozen if they become mature. Eggs that are still immature after an additional day of culture are discarded.

The cumulus cells are removed and the maturity of the eggs is assessed by embryologists. Instead of fertilizing these eggs, they are vitrified and stored in liquid nitrogen.

Then,whenever womenare ready to conceive we would then thaw the oocytes and fertilize them via ICSI. We cannot fertilize with conventional IVF treatment due to the fact we had to remove the cumulus cells to freeze them.Cumulus cells help the communication between the egg and sperm for conventional fertilization in IVF.

Eggs are frozen by vitrification (rapid freezing) and stored in liquid nitrogen tanks. The vitrification method has a higher egg survival rate compared to the old-fashioned
slow freezing method, and has therefore become the preferred method for egg freezing nowadays


How long can the oocytes be stored?

Eggs can be frozen as long as you need them. In India, by law we can freeze them for next 5 years. Pregnancies have been reported from embryos stored for 16 years.

Are there any increased birth defects or genetic defects with frozen eggs?

There is no increase in birth defects or genetic defects with frozen eggs. And alsothere are no increased risks of pregnancy complications by using egg freezing.

What are the draw backs in oocyte freezing?

1) Increased cost factor for freezing

2) Rarely eggs may not survive the thaw process during planned ICSI treatment.

3) Trained personnel are required for freezing.

Is egg freezing better than the embryo freezing?Embryo freezing is better as:                                                                                               1) Frozen embryos are more stable than frozen oocytes.                                                     2) We can access the embryo quality formed after ICSI procedure.

Can frozen oocytes be donated or discarded if not required?

Oocytes cannot be donated from patients who have given their sample at the fertility centre. It can be discarded or be used for research or teaching purpose with women’s permission.

Does the person need to pay for oocytes freezing if required to extend for certain period?

Constant maintenance of oocytes freezing need frequent use of liquid nitrogen to fill the cryo tank. Fixed charges should be paid periodically once in every 6 months or every 12 months.


  • Oocyte surrounded by cumulus cells
  • Immature oocyte with visible germinal vesicle (GV)
  • immature oocyte in first metaphase (M I)
  • mature oocyte in second metaphase (M II) with clearly visible first polar body (PB1)